STPM32 datasheet(32/89 Pages) STMICROELECTRONICS

32 / 89 page

Figure 37. Power sign status bit delay

Power

Sign

t < T/2

t = T/2

8.4.6

Calculation of power and energy

In the following section, constant parameters, coming from the device architecture, are used:

Table 12. STPM3x internal parameters

Parameter

Value

Voltage reference

VREF = 1.18 [V]

Decimation clock

DCLK = 7812.5 [Hz]

Integrator gain

(for Rogowski coil only)

kint = 1

If ROC bit = 0 in DSP_CR1,2

kint = 0.8155773

If ROC bit = 1 in DSP_CR1,2

Basic calculations are listed in Table 13:

Table 13. STPM3x basic calculations

Parameter

Voltage

Current Shunt

Current CT

Current RoCoil

Gain

AV=2

AI=16

AI=2

AI=16

Calibrators(1)

calV=0.875

calI=0.875

Sensitivity

R2R1+R2 V/A kS=RSℎuntΩ kS=RbNV/A kS=kRoCoilV/A

Voltage at channel

inputs

VinV= R2R1+R2∙V V

VinC=kS∙I V

Integrator gain (only for

Rogowski Coil sensor)

kint=1

kint=0.8155773

ΣΔ bit stream(2)

VΣΔ=VinV∙ AVVref

IΣΔ=VinC∙ AIVref

IΣΔ= VinC∙AI

Vref∙kint

Input active power

Pin=V∙I∙cosφ=V∙I W

Active power

P=VΣΔ∙calV∙IΣΔ∙calC∙cosφ

LED freq at rated

power(3)

LEDf= P∙DClk

LED_PWM∙2Hz

Constant pulse

CP=LEDfPinpulsesWs =3600000∙LEDf

Pin pulseskWℎ

CP=12∙ R2R1+R2∙kS∙kint∙AV∙AI∙calV∙calI

Vref2 ∙ DClk

LED_PWM pulsesWs

Pulse value

Ppulse= 1CP Wspulses

Power register

normalized

pn Pnorm= −1∙228∙pn 28+pn 27:0

228

STPM32, STPM33, STPM34

Functional description of hardwired DSP

DS10272 - Rev 13

page 32/89

STPM32 Datasheet(PDF) 32 Page - STMicroelectronics

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